1. Field of the Invention
This invention is related generally to network linkage diagnostic testing and, more particularly, to a system and method for using sections of a digitally wrapped communication to provide an added function of in situ inter-link testing.
2. Description of the Related Art
Bit error rate testers (BERTs) are commonly used to diagnose and determine the performance of almost any kind of communication link. They do this by generating pseudo-random test patterns and then analyzing those patterns for various problems such as bit errors, synchronization losses, and pattern slips. Unfortunately, these testers require that the normal traffic flow be interrupted, and the system rewired to inject the signal from the BERT. There is no standard practice for performing BERT analysis for data in a variable rate FEC system implementing a multiple row, byte-interleaved, multi-frame superframe structure at high speeds.
It would be advantageous if links tests could be performed without interrupting the normal communication flow.
It would be advantageous if BERT could be performed simultaneously with the transfer of normal communications.
It would be advantageous if a digitally wrapped communication format could accommodate a testing process, in addition to the normal communication process.
Accordingly, an integrated circuit (IC) relay device is presented that provides for a built-in error injection/analysis for the purpose of diagnosing fiber optic links between nodes. The analysis is performed without the necessity of using special test equipment or physically reconfiguring the network. The IC relay programmable features permit a network administrator to inject known patterns into the optical network and remotely analyze the results to determine the performance of the communication link. This performance testing can be done with only a slight reduction in data carrying capacity, and without interrupting the normal flow of traffic.
The IC relay performs the following functions:
PRBS (pseudo-random bit sequence) pattern injection into any or all subframes of a frame;
programmable PRBS pattern selection including user programmable patterns;
programmable error injection into any or all of the subframes, including the selection of which bytes are corrupted, and how they are corrupted; and
PRBS Pattern analysis on the decode side to gather error statistics on any or all of the subframes.
Critically, a network""s bit error rate performance can be measured while it is in service. This function is performed by incorporating the BERT into the IC relay invention and making the subframes affected by the BERT programmable.
A method is also provided for diagnosing errors in multidimensional digital frame structure communications. The method comprises: defining a plurality of sub-sections in each frame; from the plurality of sub-sections, selecting a first sub-section; inserting test patterns into the first sub-section; transmitting the frame from a first node; receiving the frame at a second node; and, extracting the test pattern from the first sub-section. Further details of the BERT method and IC relay are provide below.